But he says he is being harassed by a campaign to overturn his monopoly.

Mr Coop said: “The campaign against me is a witch hunt, it has become a very personal thing and I don’t think it’s ­justified. It’s been devastating, horrible.

“They are encouraging people to ­bombard me with hate mail and threats. I’ve had to report stuff to the police.”

The Keep Calm posters were first discovered by book store owner Stuart Manley, 70.

The slogan was dreamed up in 1939 as a rallying call during World War II but the posters were never issued.

In 2000, Mr Manley, the ­owner of Barter Books in ­Alnwick, Northumberland, found one of the few surviving posters in a box of books he had bought at an ­auction.

His wife Mary, 71, put it on the wall and customers began asking for copies. By December 2005 they were selling 9,000 posters a month.

But Mr Manley says former TV producer Mr Coop, from ­Weybridge, Surrey, bought a poster from their shop, cut their name off and launched his own business, ­selling everything from hoodies to chocolate bars tagged with the ­slogan.

Mr Coop also bought the website name keepcalmandcarryon.com.

Last year Euro officials granted him a Europe-wide trademark.

“We don’t mind Mr Coop selling Keep Calm stuff but surely it can’t be right that he can stop anyone else selling it too,” said Mr Manley.

He believes Mr Coop has sold £2.5million worth of Keep Calm merchandise in the last five years and is still pocketing around £400,000 a year.

An independent campaign group has seen more than 3,000 people worldwide sign up to an e-petition condemning Mr Coop. They have posted ­comments on keepcalmcampaign.co.uk calling for him to be punched, kicked and even have his head chopped off.

Newcastle lawyer Niall Head-Rapson is helping the Manleys and hopes to get Mr Coop’s EU ­ruling overturned this week.

“I would be disappointed if Mr Coop’s trademark was ­allowed to stand,” he said.